Field
The present disclosure generally relates to the design of Ion Mobility Spectrometer (IMS). More specifically, the present disclosure relates to design of a Spatially Alternating Asymmetric Field Ion Mobility Spectrometry (SAAF IMS) which allows for direct current (DC)-only control of the device operation, and various hybrid high-Field Asymmetric Ion Mobility Spectrometer (FAIMS)/IMS devices which allow for direct DC-only control of both FAIMS and IMS ion detection.
Related Art
Ion Mobility Spectrometer (IMS) is an analytical device for separating and identifying ionized molecules in the gas phase based on their mobility in a carrier buffer gas. In a traditional IMS device, ionized species in a carrier gas travel through a drift tube which applies an electric field to the ions. The separation of gas-phase ions occurs within the drift tube based on the different ion mobility of the ionized species. Typically, ion mobility is a function of both the applied electric field and gas density. By measuring time for ions to travel from one side of the drift tube to another, velocity can be determined. A special type of IMS is a high-Field Asymmetric Ion Mobility Spectrometer (FAIMS), which is capable of separating gas-phase ions at atmospheric pressure and at room temperature. Typically, FAIMS uses time-varying, high-voltage, high-frequency electric field to separate ions based on the fact that ion mobility depends on the non-linearity of the field.
However, because FAIMS requires using a waveform generator to generate the high-strength, high-frequency field, FAIMS typically has high power consumption. In addition, FAIMS requires a gas propulsion system to drive the carrier gas. Unfortunately, use of a gas propulsion system and waveform generator hinders the ability to reduce the physical dimension of FAIMS into portable devices.
Hence, what is needed is IMS device that is capable of performing FAIMS functions without the problems described above.